Outlet arrangement for an arc quenching chamber



United States Patent 3,197,596 GUTLET ARRANGEMENT FQR AN ARC QUENCHIWG CHAMEER Emil Lange, 65 rue tie Versailles, Ville dAvray, France, assignor of one-half to Aktieselskahet National lindustri, Drammen, Norway Filed Dec. 1, 1961, Ser. No. 189,656 Claims priority, application Germany, Dec 2, 1969 I. 37,677; Dec. 23, 1960, L 37,8tl4 2 Claims. (Cl. 2t)tl143) This invention relates to an outlet arrangement for the arc quenching chamber of an electric circuit-breaker of the kind in which at least one are is quenched by fluid quenching medium flowing towards and through an outlet passage of the quenching chamber under pressure produced by the are or arcs.

The invention is intended to provide an improved outlet arrangement such that the arc is quenched efiiciently both when the current being interrupted is the same as or only slightly exceeds that normally carried by the circuit and when the current is greatly excessive, for example in the event of a short-circuit.

According to the invention there is provided an outlet arrangement for the arc quenching chamber of an electric circuit-breaker of the kind in which at least one are is quenched by fluid quenching medium flowing towards and through an outlet passage ofothe quenching chamber under pressure produced by the are or arcs, wherein a choke element is held so that it partially obturates the outlet passage until the said pressure exceeds a predetermined limit and then the choke element moves to free the outlet passage. Preferably the choke element has a passage of smaller cross-section than the outlet passage, and it is very advantageous if the choke element is held by holding means which yield suddenly upon the said pressure exceeding the said limit. Further and optional features of the invention appear from the following description and claims.

The invention is illustrated by way of example in the accompanying drawings, 7

FIGURES l, 2 and 3 being sectional elevations of a switch embodying the invention, in the closed position, during breaking of a normal current, and during breaking of an excessive current, respectively, and

FIGURES 4 and 5 being respectively a sectional elevation and an end View of an electric safety fuse embodying two arrangements in accordance with the invention.

The switch shown in FIGURES l to 3 comprises an arc quenching chamber 1 full of fluid quenching medium and provided with a fixed annular contact 2 near to an outlet passage 3 and penetrated by an axially movable switch pin 4 having an arc terminal 6 and a contact surface 5 which engages the contact 2.

In the outlet passage 3 a choke element 7 with a tubular terminal 12 and a passage 8 of smaller cross-section than the passage 3 is held by holding means comprising a slider 9 which has passages 10 and slides axially on a guide pin 21 secured to a frame or casing 22 fixed to the chamber 1. A valve 11 is axially slidable within the slider 9 and is loaded by a compression spring 13. The slider 9 has external cam surfaces 14, 15 and 16.

On two pivots 17 fixed in the casing 22 are mounted two levers 18 loaded by leaf springs 20 and carrying detent springs 19.

A deflector 23 is secured inside the casing and has a clearance aperture for the slider 9.

In the initial or closed position shown in FIGURE 1 the current passes through the switch pin 4 and the fixed contact 2. The choke element 7 is held in and partially obturates the outlet passage 3, the terminal 12 projects beyond the fixed contact 2, the valve 11 closes the passages 8 and It), and the arc terminal 6 projects into the passage 8. The lower ends of the levers 18 rest on the surfaces 15, and the detent springs 19 are spaced a predetermined distance from the surfaces 16.

When the switch is to be opened the contact 2 is isolated from the circuit and the current passes through the slider 9 and choke element 7 and switch pin 4, then the latter is moved downwardly.

If a normal current is being interrupted the switch operates as indicated in FIGURE 2. An arc A is formed and produces in the quenching medium a pressure such that the slider 9 rises until stopped by the surfaces 16 engaging the detent springs 19, the valve rises to open the passages 8 and Ill, and the quenching medium under pressure flows towards and through these passages, the pressure and flow being such as to efficiently quench the are which has one root on the terminal 12.

i an excessive current is being interrupted the action is initially as described with reference to FIGURE 2 in interrupting a normal current, but the powerful arc causes a sudden increase of pressure exceeding the predetermined limit whereupon the switch operates as indicated in FIGURE 3. The pressure forces the slider up against the action of the detent springs 19 until the lower ends of the levers pass from the surfaces 15 to the surfaces 14 and then the holding means yield suddenly, the levers 1S turning on their pivots 17 so that the detent springs 19 clear the surfaces 16. The switch then reaches the position shown in FIGURE 3, the arc AA extending through the outlet passage 3 and being subjected to very eflicient action of the quenching medium.

When the pressure is sufiiciently reduced the spring 13 returns all parts except th e switch pin 4 to the position shown in FIGURE 2, and then to the initial position shown in FIGURE 1.

Various modifications may be introduced without departing from the invention, for example instead of the holding and detent means illustrated the choke element 7 may be connected to a piston sliding in a cylinder containing air which is compressed and then suddenly released when the pressure of the quenching medium exceeds a predetermined limit.

The fuse shown in FIGURES 4 and 5 comprises a quenching chamber 26 fitted with contact sleeves 43 and accommodating insulating inserts 44 and 45 and conducting inserts 46, the latter supporting electrodes 32 and 33 by means of radial struts (not shown). The inserts 44 define outlet passages 27 and 28; the insert 45 defines a pressure space 29, and the inserts 46 define storage spaces 30 and 31. By means of screws 40 apertured rupturable retainers 38 and 39 are secured to the sleeves 43. At tached to the retainers 38 and 39 are apertured valve elements 36 and 37 which rest against the inserts 44 and partially obturate the outlet passages 27 and 28 and hold tubular choke elements 34 and which are of insulating material and project into and partially obturate but are not gripped in the outlet passages 27 and 28. A fuse wire 41 has one end soldered to the retainer 38 and passes through the interior of the quenching chamber 26 and has its other end secured by one of the screws 40.

If an excessive current melts the fuse wire 41, there i s at first a single long arc with its roots on the retainers 38 and 39, but this quickly divides into three shorter arcs of which one is between the retainer 38 and electrode 32, one is between the electrodes 32 and 33 and efficiently producing pressure in the space 29, and one is between the electrode 33 and retainer 39.

If the current is not greatly excessive, the pressure produced by the arcs, particularly in the space 29, causes etficient quenching of the arcs in the choke elements 34 3 and 35 but is not sufficient to rupture the retainers 38 and 39.

If the current is greatly excessive the pressure produced by the long are or the three shorter arcs is suflicient to rupture one or both of the retainers 38 and 39, one or both of the choke elements 34 and 35 being suddenly expelled to free one or both of the outlet passages 27 and 28 in which the arc is very efficiently quenched.

The choke elements 34 and 35 may be of different dimensions, the passages 27 and 28 may be of different dimensions, or the retainers 38 and 39 may be of different strengths, in order to extend the range within which the fuse functions efficiently, and various modifications may be introduced without departing from the invention; preferably cages or the like are provided for catching the choke elements 34 and 35 when the latter are expelled, and the choke elements are formed of material which under the action of the arcs generates gas which aids the quenching of the arcs, and they may be formed integrally with the valve elements 36 and 3'7.

In the switch and fuse described above the quenching medium may be any desired gas or liquid with or without inert or other powder which aids the quenching of'the arcs.

I claim:

1. In an electric switch the combination including an arc-quenching chamber, fluid quenching medium within said chamber, an outlet passage of said chamber, a casing secured to said chamber, a guide pin secured to said casing, a tubular slider mounted on said guide pin for axial movement toward and away from said outlet passage, a tubular choke element carried by said slider for extending with clearance into and partly obturating said outlet passage, cam surfaces on said slider, a plurality of springloaded levers mounted within said casing and each having one end resting on one of said cam surfaces, a plu rality of detent springs each secured to one of said levers and disposed for engaging one of said cam surfaces for resisting displacement of said slider in a direction away from said outlet passage, and a movable switch pin in said chamber for drawing from said choke element an arc creating pressure within said quenching medium upon opening of said electric switch, said slider moving under the pressure of said quenching medium in opposition to said detent springs until upon the pressure of said quenching medium exceeding a predetermined limit said cam surfaces allow said levers to turn and so move said detent springs for sudden release of said slider to carry said choke element clear of said outlet passage.

2. In an electric switch the combination as claimed in claim 1, further including lateral openings in said slider and a valve inside said slider spring-loaded towards closing said tubular choke element, said valve being arranged to move under the pressure of said quenching medium and allow fiow of said quenching medium through said choke element and said lateral openings in said slider before said I detent springs release said slider.

References Cited by the Examiner UNITED STATES PATENTS 1,336,069 4/20 Conrad 200 2,052,232 8/36 Kopeliowitch et a1 200150 2,387,5 89 10/45 Kesselring et al 200150 2,925,484 2/60 Thommen 200148 ROBERT K. SCHAEFER, Acting Primary Examiner.

BERNARD A. GILHEANY, Examiner. 

1. IN AN ELECTRIC SWITCH THE COMBINATION INCLUDING AN ARC-QUENCHING CHAMBER, FLUID QUENCHING MEDIUM WITHIN SAID CHAMBER, AN OUTLET PASSAGE OF SAID CHAMMBER, A CASING SECURED TO SAID CHAMBER, A GUIDE PIN SECURED TO SAID CASING, A TUBULAR SLIDER MOUNTED ON SAID GUIDE PIN FOR AXIAL MOVEMENT TOWARD AND AWAY FROM SAID OUTLET PASSAGE, A TUBULAR CHOKE ELEMENT CARRIED BY SAID SLIDER FOR EXTENDING WITH CLEARANCE INTO AND PARTLY OBTURATING SAID OUTLET PASSAGE, CAM SURFACES ON SAID SLIDER, A PLURALITY OF SPRINGLOADED LELVERS MOUNTED WITHIN SAID CASING AND EACH HAVING ONE END RESTING ON ONE OF SAID CAM SURFACES, A PLURALITY OF DETENT SPRINGS EACH SECURED TO ONE OF SAID LEVERS AND DISPOSED FOR ENGAGING ONE OF SAID CAM SURFACES FOR RESISTING DISPLACEMENT OF SAID SLIDER IN A DIRECTION AWAY FROM SAID OUTLET PASSAGE, AND A MOVABLE SWITCH PIN IN SAID CHAMBER FOR DRAWING FROM SAID CHOKE ELEMENT AN ARCCREATING PRESSURE WITHIN SAID QUENCHING MEDIUM UPON OPENING OF SAID ELECTRIC SWITCH, SAID SLIDER MOVING UNDER THE PRESSURE OF SAID QUENCHING MEDIUM IN OPPOSITION TO SAID DETENT SPRINGS UNTIL UPON THE PRESSURE OF SAID QUENCHING MEDIUUM EXCEEDING A PREDETERMINED LIMIT SAID CAM SURFACES ALLOW SAID LEVERS TO TURN AND SO MOVE SAID DETENT SPRINGS FOR SUDDEN RELEASE OF SAID SLIDER TO CARRY SAID CHOKE ELEMENT CLEAR OF SAID OUTLET PASSAGE. 